1. Field of the Invention
The present invention relates to an aromatic liquid crystal polyester and a process for producing the same.
2. Description of Related Arts
Liquid crystalline polyesters (aromatic liquid crystal polyester) comprising an aromatic ring skeleton are used recently in the electric and electronic fields as high performance materials excellent in mechanical properties such as strength, elastic modulus and the like, and in heat resistance.
As the process for producing an aromatic liquid crystal polyester, the following processes (1) and (2) are known using an aromatic hydroxycarboxylic acid such as p-hydroxybenzoic acid and the like, an aromatic diol such as 4,4′-hydroxybiphenyl and the like and an aromatic dicarboxylic acid such as terephthalic acid and the like, and acetic anhydride as an acylating agent.
(1) A process in which a phenolic hydroxyl group in an aromatic diol and/or aromatic hydroxycarboxylic acid is acylated with acetic anhydride to obtain an acylated compound, and this acylated compound is allowed to react with a carboxyl group in an aromatic dicarboxylic acid and/or aromatic hydroxycarboxylic acid by a transesterification reaction.
(2) A process in which an aromatic diol and/or aromatic hydroxycarboxylic acid are reacted with an aromatic dicarboxylic acid in the presence of acetic anhydride to effect the acylation reaction and transesterification reaction in the process (1).